Enantioselective Metabolism of Quizalofop-Ethyl in Rat

<div><p>The pharmacokinetic and distribution of the enantiomers of quizalofop-ethyl and its metabolite quizalofop-acid were studied in Sprague-Dawley male rats. The two pairs of enantiomers were determined using a validated chiral high-performance liquid chromatography method. Animals were administered quizalofop-ethyl at 10 mg kg⁻¹ orally and intravenously. It was found high concentration of quizalofop-acid in the blood and tissues by both intragastric and intravenous administration, and quizalofop-ethyl could not be detected through the whole study which indicated a quick metabolism of quizalofop-ethyl to quizalofop-acid in vivo. In almost all the samples, the concentrations of (+)-quizalofop-acid exceeded those of (−)-quizalofop-acid. Quizalofop-acid could still be detected in the samples even at 120 h except in brain due to the function of blood-brain barrier. Based on a rough calculation, about 8.77% and 2.16% of quizalofop-acid were excreted through urine and feces after intragastric administration. The oral bioavailability of (+)-quizalofop-acid and (−)-quizalofop-acid were 72.8% and 83.6%.</p></div

Chemical structures of QE and its primary metabolite QA.

<p>Chiral center is denoted by an asterisk (*).</p

The EF value in brain, kidney, lung, liver, urine and feces.

<p>The EF value in brain, kidney, lung, liver, urine and feces.</p

Pharmacokinetic parameters and bioavailability of QA after intravenous and oral administration (n = 6).

<p>Pharmacokinetic parameters and bioavailability of QA after intravenous and oral administration (n = 6).</p

Calibration data of QE and QA enantiomers in different sample matrixes.

<p>Calibration data of QE and QA enantiomers in different sample matrixes.</p

EF-time curve of QA in blood after intravenous administration.

<p>EF-time curve of QA in blood after intravenous administration.</p

EF-time curve of QA in blood after intragastric administration.

<p>EF-time curve of QA in blood after intragastric administration.</p

Enantioselective Characteristics and Montmorillonite-Mediated Removal Effects of α‑Hexachlorocyclohexane in Laying Hens

α-Hexachlorocyclohexane (α-HCH) is a chiral organochlorine pesticide that is often ubiquitously detected in various environmental matrices and may be absorbed by the human body via food consumption, with serious detriments to human health. In this study, enantioselective degradation kinetics and residues of α-HCH in laying hens were investigated after a single dose of exposure to the pesticide, whereas enantioselectivity and residues of α-HCH in eggs, droppings, and various tissues were investigated after long-term exposure. Meanwhile, montmorillonite (MMT), a feed additive with high capacity of adsorption, was investigated for its ability to remove α-HCH from laying hens. Most non-brain tissues enantioselectively accumulated (−)-α-HCH, while (+)-α-HCH was preferentially accumulated in the brain. The enantiomer fractions (EFs) in most tissues gradually decreased, implying continuous depletion of (+)-α-HCH in laying hens. After 30 days of exposure and 31 days of elimination, the concentration of α-HCH in eggs and tissues of laying hens with MMT-containing feed was lower than that with MMT-free feed, indicating the removal effects of MMT for α-HCH in laying hens. The findings presented herein suggest that modified MMT may potentially be useful in reducing the enrichment of α-HCH in laying hens and eggs, thus lowering the risk of human intake of α-HCH

Excretion rate of (+)-QA (ER₁) and (−)-QA (ER₂) by urine and feces.

<p>Excretion rate of (+)-QA (ER₁) and (−)-QA (ER₂) by urine and feces.</p